Differentials in mortality by socio-economic status have been documented in the USA and UK. Less is known about health related functioning in the physiological, psychological and social role. These aspects are important in studies of medical outcomes, and it is necessary to examine factors other than medical care which are related to functioning. This study will test the use of a potentially valuable tool, the General Health Survey used in the Medical Outcome study (MOS-GHS), in a cross national study. A prospective study (Whitehall II) has been set up to examine causes of socioeconomic inequalities in health among civil servants in London. The present proposal seeks to supplement this study with measures of health related functioning. The objectives are: a) to validate the MOS-General Health Survey in a general population sample in Britain b) to examine the relationship between functional status and other self-reported and measured components of health c) to examine the relationships between socio-economic status, functional status, and perceived well-being d) to assess the impact on functional status and perceived well being of features of lifestyle, work environment, social networks and types of social support, and socioeconomic circumstances, both current and during childhood, e) to establish a cohort in which the prospective significance of functional status can be investigated. Subsequent sickness absence, major morbidity and mortality will be related to the baseline measures of functional status. These objectives will be met through the enhancement of the Whitehall II study. In this study a cohort of 10,314 male and female civil servants aged 35-55 completed an extensive questionnaire and a screening examination between 1985 and 1988. In 1989 a repeat questionnaire survey was carried out. The cohort is being followed through sickness absence records, major morbidity reporting and mortality registrations. The cohort will be rescreened in 1991-1992. This proposal seeks to include the MOS-GHS and other measures of functioning in the study at the time of this rescreen. Selfcompletion questionnaires will be given to the entire cohort, with a random subsample of 200 participants undergoing a validation interview. Data from this survey will be linked to the data from the baseline study, the repeat questionnaire survey, sickness absence reports, major morbidity recording and mortality and cancer registrations.